Hydronic Rules of Thumb

Mon, September 09, 2016

Do you know enough to be dangerous?

True or False: Hydronic heating systems offer the maximum amount of comfort and efficiency possible to their owners. The answer, of course, is False! What is True, is that properly designed and installed hydronic systems offer the maximum amount of comfort and efficiency. Hydronic or otherwise, improperly designed systems have the same problems: hot and cold areas, large temperature swings, and inefficient operation. For over the fifty years, the ultimate resource for hydronic design and equipment has been Bell & Gossett. With over 60,000 graduates, The Little Red School House, at the B&G factory in Morton Grove, has literally educated our industry, and all at no charge! Visit your local stocking B&G Wholesaler and learn to properly design hydronic heating systems. Learn about Primary Secondary pumping, Zoning Made Easy, Flow and Head Loss Calculations, Air Control, and Point of No Pressure Change to name a few. Learn to design and install the most comfortable, most efficient heating system available. Before you get the chance to attend a class, here are ten simple rules of thumb for designing hydronic systems:

1. PSI x 2.31 = feet of head (TDH)
2. GPM x Delta T x 500 = BTU/hour
3. Pressure Drop for piping system = Linear Feet of Longest Circuit x .06
4. Proper flow for boiler in GPM = Output BTU/hr. divided by 10,000
5. Static Height in feet / 2.31 + 4 PSI = Proper fill pressure
6. Maximum Capacity
   • 1/2" Pipe = 1.3 GPM = 13,000 BTU/hr.
   • 3/4" Pipe = 3.5 GPM = 35,000 BTU/hr.
   • 1" Pipe = 7.5 GPM = 75,000 BTU/hr.
   • 1-1/4" Pipe = 12 GPM = 120,000 BTU/hr.
   • 1-1/2" Pipe = 20 GPM = 200,000 BTU/hr.
   • 2" Pipe = 45 GPM = 450,000 BTU/hr.
7. Maximum output radiant floor = 35 BTU / square foot
8. Typical output snowmelt system = 125 BTU / square foot
9. Estimate for heat loss of New Building = 35 BTU / square foot
10. Estimate for heat loss of Old Building = 50 BTU / square foot

Visit your local B&G Stocking Wholesaler to be enrolled in a Little Red Schoolhouse class, for design or maintenance.